Haniger will serve as the Mariners' designated hitter and No. 8 batter in Monday's game against the Red Sox.
Haniger will nab his fifth straight start Monday after producing two extra-base hits and drawing five walks over the past four contests. His recent success at the plate could be enough for Haniger to remain a regular in the lineup for the time being, but he'll be at risk of moving into a part-time role as soon as his bat cools down.